1. Field of the Invention
This invention is in the field of internal combustion engines and particularly the field of internal combustion engines burning solid fuels alone or in combination with liquid or gaseous fuels.
2. Description of the Prior Art
Efforts have been made in the past to burn solid fuels, in pulverized form, in internal combustion engines, either alone or in combination with liquid or gaseous fuels (see reference G and references 1, 2 and 3 therein). When run with diesel fuel pulverized coal could be burned at least partially in an internal combustion engine (see references H and K). None of these prior art efforts produced an engine commercially successful for a long time period and all present-day internal combustion engines in common use burn gaseous and/or liquid fuels only.
Certain mechanical portions of the internal combustion engines of my invention are already well known in the prior art such as the pistons, cylinders, crankshafts, etc. The term "internal combustion engine" is used hereinafter and in the claims to mean these already well known combinations of cylinders, cylinder heads, pistons operative within said cylinders and connected to a crankshaft via connecting rods, valves and valve actuating means or cylinder ports, cams and camshafts, lubrication system, cooling system, ignition system if needed, flywheels, starting system, fuel supply system, fuel air mixing system, intake pipes and exhaust pipes, superchargers, torque control system, etc. as necessary or desired for the operation of said internal combustion engine. The term "internal combustion" is used hereinafter and in the claims to include also the already well-known combinations as described above but wherein the cylinders, cylinder heads, pistons operative within said cylinders and connected to a crankshaft via connecting rods, valves and valve actuating means or cylinder ports, are replaced by a rotary engine mechanism combination, comprising a housing with a cavity therein, and plates to enclose the cavity, a rotor operative within said cavity and sealing off separate compartments within said cavity and connecting directly or by gears to an output shaft, ports in said housing for intake and exhaust, such as in the "Wankel" type engine. An internal combustion engine may be of the four stroke type, wherein for each cylinder two full engine revolutions or processes are required to complete a single engine cycle of intake, compression, combustion, expansion and exhaust, or alternatively may be of the two stroke type wherein a single engine cycle is completed for each cylinder, within a single engine revolution or process, as is well known in the art of internal combustion engines.
The term "internal combustion engine mechanism" is used herein and in the claims to mean all those portions of an internal combustion engine, as defined hereinabove, except the fuel supply system, fuel-air mixing system, torque control system and any spark ignition apparatus. The term, "piston and cylinder," is used herein and in the claims to mean these elements of an internal combustion engine as commonly used in piston and cylinder engines, and also the functionally corresponding elements as used in other engine types such as the Wankel engine, and further includes cases where more than one piston is used in each cylinder.
The term "char fuels" is used hereinafter and in the claims to mean any fuel, capable of reacting chemically with oxygen to release chemical energy, whose usual physical state is wholly or largely solid or which leaves behind a solid residue after volatile matter has been evolved. Included within this definition of char fuel are such common and well known fuels as coal, coke, charcoal, coal char, petroleum char, wood, lignite, peat, petroleum coke, certain residual petroleum fuels, etc. Certain of these fuels, such as wood and certain types of coal, are known to evolve gaseous and liquid fuel components when heated and these evolved gaseous and liquid fuel components are hereinafter referred to as "volatile matter." All of the above defined char fuels are either already solid or leave behind a solid, largely carbonaceous, residue hereinafter referred to as "fixed carbon." Many of the above defined char fuels are also known to contain ash-forming ingredients which leave behind a non-burnable residue after the fuel has been burned with oxygen and this non-burnable residue is hereinafter and in the claims referred to as the "ash."
The inability of prior art internal combustion engines to readily burn char fuels is a deficiency of these engines. In the past this deficiency of prior art internal conbustion engines has been significant in only certain applications, such as in railroad engines, since gaseous and liquid fuels have been in plentiful supply heretofore. Now, however, the rapidly increasing use of internal combustion engines combined with the increasing cost and difficulty of finding new sources of liquid and gaseous fuels has made this deficiency of prior art internal combustion engines a significant problem in many more applications. Presently known reserves of solid fuels, particularly coal, are, on the other hand, many-fold greater than known reserves of petroleum and natural gas. It will clearly be a great public benefit if these readily available char fuels can be used in the highly efficient and convenient internal combustion engine. That this is so is amply demonstrated by the large amounts of public and private research money and effort being now expended in an effort to discover satisfactory ways to liquify coal in order to make it useable in prior art internal combustion engines.
The ease of handling and refueling with liquid fuels combined with their usually high energy density make them preferred fuels for passenger cars and especially for aircraft. Hence, we desire to make as much as the coal into a liquid fuel as is economically and conveniently possible. Several processes are already well known in the art for the devolatilization of coal whereby the volatile matter of the coal is largely removed and converted into valuable liquid and gaseous fuels. Most of these processes are of low cost and use up only a lesser portion of the chemical energy of the coal. The thusly devolatilized coal leaves behind a coal char material, constituting perhaps 40 to 75 percent of the original coal, which is usually very porous, essentially all solid material and highly carbonaceous. Efforts to liquify or gasify this solid coal char material have proven disappointing in that the necessary processing is costly, consumes significant portions of the available chemical energy of the coal char, and yields fuel products possessing unsatisfactory characteristics.
Solid char fuels of high porosity and similar to the above-described coal char fuel can also be manufactured by the devolatilization of wood waste materials, tree bark, agricultural waste materials, garbage, and other vegetable and organic materials. Most of these vegetable-derived fuels are a renewable energy resource.